[v6.6] general protection fault in pick_link

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3a8ababb8b6a Linux 6.6.101
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=17fc0842580000
kernel config: https://syzkaller.appspot.com/x/.config?x=a2bd95b6de4839b7
dashboard link: https://syzkaller.appspot.com/bug?extid=069d26bb737cfa9917ee
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1221fea2580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10c489a2580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/f06c672f5fa8/disk-3a8ababb.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9af9b7afcdc5/vmlinux-3a8ababb.xz
kernel image: https://storage.googleapis.com/syzbot-assets/351a55aafa77/bzImage-3a8ababb.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/d4af6c5c2ad6/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+069d26...@syzkaller.appspotmail.com

ntfs3: loop0: ino=1b, "file0" ntfs_rename
general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 1 PID: 5946 Comm: syz.0.17 Not tainted 6.6.101-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:pick_link+0x52d/0xdd0 fs/namei.c:1813
Code: cd ec ff 4d 8b 2e 4d 85 ed 0f 84 a3 00 00 00 e8 09 87 95 ff 49 bf 00 00 00 00 00 fc ff df 4c 8b 74 24 20 4c 89 e8 48 c1 e8 03 <42> 0f b6 04 38 84 c0 0f 85 12 06 00 00 41 0f b6 6d 00 bf 2f 00 00
RSP: 0018:ffffc90003397848 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffffc90003397968 RCX: ffff888078330000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffffffff8e4a84ef R09: 1ffffffff1c9509d
R10: dffffc0000000000 R11: fffffbfff1c9509e R12: 1ffff92000672f93
R13: 0000000000000002 R14: ffffc90003397cc0 R15: dffffc0000000000
FS: 00005555613db500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc26c5e2000 CR3: 00000000762e9000 CR4: 00000000003506e0
Call Trace:
<TASK>
step_into+0xc3d/0xf10 fs/namei.c:1872
open_last_lookups fs/namei.c:3579 [inline]
path_openat+0x16bb/0x3190 fs/namei.c:3786
do_filp_open+0x1c5/0x3d0 fs/namei.c:3816
do_sys_openat2+0x12c/0x1c0 fs/open.c:1419
do_sys_open fs/open.c:1434 [inline]
__do_sys_open fs/open.c:1442 [inline]
__se_sys_open fs/open.c:1438 [inline]
__x64_sys_open+0x11f/0x140 fs/open.c:1438
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f17f518ebe9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe09909488 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007f17f53b5fa0 RCX: 00007f17f518ebe9
RDX: 0000000000000000 RSI: 0000000000048500 RDI: 0000200000000a80
RBP: 00007f17f5211e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f17f53b5fa0 R14: 00007f17f53b5fa0 R15: 0000000000000003
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:pick_link+0x52d/0xdd0 fs/namei.c:1813
Code: cd ec ff 4d 8b 2e 4d 85 ed 0f 84 a3 00 00 00 e8 09 87 95 ff 49 bf 00 00 00 00 00 fc ff df 4c 8b 74 24 20 4c 89 e8 48 c1 e8 03 <42> 0f b6 04 38 84 c0 0f 85 12 06 00 00 41 0f b6 6d 00 bf 2f 00 00
RSP: 0018:ffffc90003397848 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffffc90003397968 RCX: ffff888078330000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffffffff8e4a84ef R09: 1ffffffff1c9509d
R10: dffffc0000000000 R11: fffffbfff1c9509e R12: 1ffff92000672f93
R13: 0000000000000002 R14: ffffc90003397cc0 R15: dffffc0000000000
FS: 00005555613db500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc26c5e2000 CR3: 00000000762e9000 CR4: 00000000003506e0
----------------
Code disassembly (best guess):
0: cd ec int $0xec
2: ff 4d 8b decl -0x75(%rbp)
5: 2e 4d 85 ed cs test %r13,%r13
9: 0f 84 a3 00 00 00 je 0xb2
f: e8 09 87 95 ff call 0xff95871d
14: 49 bf 00 00 00 00 00 movabs $0xdffffc0000000000,%r15
1b: fc ff df
1e: 4c 8b 74 24 20 mov 0x20(%rsp),%r14
23: 4c 89 e8 mov %r13,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 42 0f b6 04 38 movzbl (%rax,%r15,1),%eax <-- trapping instruction
2f: 84 c0 test %al,%al
31: 0f 85 12 06 00 00 jne 0x649
37: 41 0f b6 6d 00 movzbl 0x0(%r13),%ebp
3c: bf .byte 0xbf
3d: 2f (bad)


---
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[syzbot]

syzbot suspects this issue was fixed by commit:

commit b35a50d639ca5259466ef5fea85529bb4fb17d5b
Author: Edward Adam Davis <ead...@qq.com>
Date: Wed Jun 18 07:31:57 2025 +0000

fs/ntfs3: cancle set bad inode after removing name fails

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1136f762580000
start commit: 3a8ababb8b6a Linux 6.6.101
git tree: linux-6.6.y

kernel config: https://syzkaller.appspot.com/x/.config?x=a2bd95b6de4839b7
dashboard link: https://syzkaller.appspot.com/bug?extid=069d26bb737cfa9917ee

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1763fea2580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=164f31a2580000

If the result looks correct, please mark the issue as fixed by replying with:

#syz fix: fs/ntfs3: cancle set bad inode after removing name fails

For information about bisection process see: https://goo.gl/tpsmEJ#bisection